(1) Field of the Invention
The present invention relates to a connecting mechanism for pole members, such as pole members used for remote control and pipes or poles for setting up a scaffolding for building.
(2) Description of the Prior Art
This invention has been made to improve a connecting mechanism for pole members, disclosed in my invention filed on Sept. 14, 1982 under U.S. Ser. No. 417,940 now U.S. Pat. No. 4,489,037 which comprises a connecting mechanism for pole members which remotely operate an apparatus for automatically adjusting a channel box fitting position relative to a nuclear fuel assembly. A ten meter pole is necessary to remotely carry out the maintenance of nuclear fuel assemblies or any other aids disposed in the center of a reactor vessel or a nuclear fuel pool, from a fuel changing machine arranged above the reactor vessel or from the sides of the pool. As such a pole member, a plurality of short poles are connected to a single pole by means of bolts in the prior art. However, any work or operations in a nuclear reactor or power plant should be strictly carried out in view of safety. If the used parts are falling into the center of the nuclear vessel or the fuel pool while changing them to the corresponding new parts, the parts fallen onto the bottom of the reactor vessel or the fuel pool must be collected certainly even if the parts is only a small bolt or nut, otherwise the nuclear reactor cannot be operated.
Accordingly, the connecting mechanism for the remote control pole member should be precisely and surely constructed even if it becomes somewhat expensive. Further, it is required to easily carry out a connecting operation of the pole members, otherwise the efficiency of parts changing work will be lowered. Therefore, such a connecting mechanism which surely connects pole members one another with a simple connecting action, was required. Then, I proposed to provide a threaded member with a pole member and to engage same with a male thread formed with another pole in the state that each of the ends of the pole members is contacted and fixedly connected each other in the direction of the common axis thereof, and to provide with each of the ends of the pole members a fittingly engaging portion which connects both the pole members to be integrally rotatable. This connecting mechanism is constructed to prevent the threaded member from releasing due to relative rotation of the pole members for operation by using a fitting engagement of the fittingly engaging portion formed with the ends of the pole members. However, there is provided a clearance for play between the fittingly engaging portions in order to easily make a fitting engagement in the direction of the common axis of the pole members. Therefore, when the pole members receive an external force due to vibration or hand operation, they are easily rotatable within the range of the clearance and thereby the threaded member of the pole member is rotated slightly relative to the other pole member. Accordingly, once the threaded member rotates slightly in the direction of release, the tightening force by the threaded member is remarkably reduced, and as, result the threaded the member is further easily totatable in the direction of release and if the pole members are used continuously, the connecting mechanism between the pole members becomes cranky and gets out of joint.